add rake tasks for web hooks management
add help page for web hooks management using rake tasks
Update logic for validates_merge_request for tree of MR

For case:

Merge request №1: branch "feature" to "release" and remove "feature" branch

Merge request №2: branch "release" to "master" and remove "release" branch

Merge request №1 - broken :(
Remove -y option when removing puby1.8

Since it is easily could break installations running on the server - hence the person doing the install should be able to make the decision to remove himself.
add link on realisation api for java client
Add 'hooks' to path blacklist.
bind unicorn listener to 127.0.0.1

otherwise it will listen on 0.0.0.0
Fix GitLab Shell version check
Fix the `service gitlab restart` command

This commit addresses two related issues:
- Sidekiq should shut down completely before we restart it;
- If we restart unicorn with USR2 we need to kill the old master and
  worker processes.
People like Karen and myself are confused by the placeholder, it seems like you don't have to change the master value. Also the to and from should be more prominent.
Select files with diff filter for graph log
Fixed 500 error when try to remove group
Merge branch 'master' of github.com:gitlabhq/gitlabhq
Update 20130419190306_allow_merges_for_forks.rb

Postgress db migrate fails.(5.4=>6.0)
Merge pull request #4860 from gitlabhq/fix_service_gitlab_restart

Fix the `service gitlab restart` command
Merge pull request #4879 from sugarmo/master

Select files with diff filter for graph log
Merge pull request #4854 from aus/patch-1

Fix GitLab Shell version check
Merge pull request #4845 from mmoll/unicorn_localhost

bind unicorn listener to 127.0.0.1
Merge pull request #4841 from Razer6/update_path_blacklist

Add 'hooks' to path blacklist.
Merge pull request #4815 from MegaDiablo/patch-1

add link on realisation api for java client